Eye Shine and Owlet Nightjars

To: Chris Corben <>, Birding Aus <>
Subject: Eye Shine and Owlet Nightjars
From: Denise Goodfellow <>
Date: Tue, 19 Nov 2013 06:18:14 +0930
Water buffalo eyes also look blue and crocodiles are red.

So if you're walking through the bush in Kakadu and you see blue eyes then
be careful (and yes, I have been in this position and it was a buffalo).

 Occasionally one can encounter a crocodile crossing land in the late dry
season.  So big red eyes, with a bit of distance between them, might be
avoided as well.  

Barramundi eyes shine red too, by the way.  Good to know if you're fishing
at night.

Denise Lawungkurr Goodfellow
PO Box 71,  Darwin River,
NT 0841
043 8650 835

PhD candidate, SCU
Vice-chair, Wildlife Tourism Australia

Nominated for the Condé Nast international ecotourism award, 2004 by the
natural history and cultural tourism American website, Earthfoot.

Wildlife Adviser, BBC¹s ?Deadly 60¹

On 19/11/13 3:39 AM, "Chris Corben" <> wrote:

> You can see eyeshine on an incredibly wide range of insects and spiders.
> As with birds, and everything else I have seen an eye-shine from, the
> colour is dependent on the viewing conditions, particularly the angle
> from which you view it in relation to the subject's head. The colour may
> also appear to change with how close you are, but that might be just a
> perception thing.
> However, it is usually obvious that some things differ in colour in
> typical viewing conditions. A Greater Glider or a cat typically look
> very bright and greenish, while most possums look more red, orange or
> yellow in most conditions. Typical Nightjars look very bright, but
> distinctly orange-reddish. Frogs when viewed well usually look whitish
> or pink. Sheep look more blue.
> Interestingly, Owls, Frogmouths and Owlet Nightjars generally don't look
> very bright, despite that they are very nocturnal. There is a huge
> difference in eyeshine brilliance between a typical Nightjar and a
> Frogmouth!
> Cheers, Chris.
> On 11/18/2013 06:57 AM, Andrew Hobbs wrote:
>> Ooops.
>> As  Philip Veerman reminded me (at least to me), arachnids are not
>> insects of course .  So while I had thought that their eyes are
>> compound eyes, in fact they have multiple simple eyes or ocelli.
>> Andrew
>> On 18/11/2013 8:08 PM, Andrew Hobbs wrote:
>>> Given the nature of insect eyes, is it possible that you are seeing
>>> some sort of irridescent effect, similar to the irridescent colours
>>> seen in some insects and bird feathers etc. (due to diffraction,
>>> multiple reflections and interference etc.)
>>> Andrew
>>> On 18/11/2013 7:03 PM, Denise Goodfellow wrote:
>>>> And wolf spiders' eyes (for that's what you're seeing), appear to
>>>> change
>>>> colour as you approach them!
>>>> Denise
>>>> Denise Lawungkurr Goodfellow
>>>> PO Box 71,  Darwin River,
>>>> NT 0841
>>>> 043 8650 835
>>>> On 18/11/13 6:24 PM, "Mona Loofs Samorzewski"
>>>> <>
>>>> wrote:
>>>>> Thanks Andrew for that excellent explanation.
>>>>> Along the same vein, I have walked around the bush at Howard
>>>>> Springs near
>>>>> Darwin at night with a head torch on, and seen many many
>>>>> reflections coming
>>>>> from the ground from spiders eyes. And they were blue! A friend with a
>>>>> hand-held torch wasn't seeing them at all until he put my head
>>>>> torch on. And
>>>>> then we realised how many spiders we were walking on...
>>>>> Mona
>>>>> On 18/11/2013, at 4:54 PM, Andrew Hobbs wrote:
>>>>>> There are two types of 'eye shine'.
>>>>>> As Chris said it is partly simple physics. By the nature of the
>>>>>> eye and its
>>>>>> focus on the back of the eye when light is shone into it there is a
>>>>>> reflection from the back of the eye. As is the case with anything
>>>>>> being
>>>>>> illuminated, at least some of the light is reflected back along
>>>>>> the same path
>>>>>> and will appear to cause the eye to 'shine' (compared to the rather
>>>>>> non-reflective coat of hair, feathers etc).
>>>>>> But there is another factor.  Some animals (including some birds
>>>>>> such as
>>>>>> owls) which are active at night, have a layer at the back of the
>>>>>> eye called a
>>>>>> 'Tapetum Lucidum'.  This layer contains mineral crystals which
>>>>>> have the
>>>>>> property of reflecting almost all the incident light back along
>>>>>> the same path
>>>>>> as the incident light. (Look up 'Corner reflector' on Wikipedia)
>>>>>> This layer
>>>>>> is behind the layer of light sensitive cells, doubling the
>>>>>> sensitivity of the
>>>>>> eye. (The cells have two chances of capturing photons; coming and
>>>>>> going).
>>>>>> When you shine a light into an animal or bird with these eyes they
>>>>>> really do
>>>>>> appear to shine very brightly. However the reflection is not
>>>>>> perfect and some
>>>>>> light is reflected back somewhat 'off axis'. In this case, because
>>>>>> the
>>>>>> reflection is so strong, you can still see a reflection even if
>>>>>> your eyes are
>>>>>> well off the same axis as the torch beam.
>>>>>> In contrast, in animals (and birds) without a Tapetum Lucidum, the
>>>>>> light is
>>>>>> reflected of the Fundus at the back of the eye.  This is not a
>>>>>> good reflector
>>>>>> but some does get reflected back along the axis.  Because the
>>>>>> reflection is
>>>>>> so much weaker your eyes need to be much closer to the axis of the
>>>>>> torch beam
>>>>>> to see the effect.
>>>>>> The colour of the eye reflection from the Tapetum Lucidum depends
>>>>>> upon the
>>>>>> properties of the crystals in the layer.  It can vary more or less
>>>>>> across the
>>>>>> full visible spectrum.  However in animals without that layer the
>>>>>> reflection
>>>>>> is always red.  The red colour is mainly due to the haemoglobin in
>>>>>> the blood
>>>>>> vessels at the back of the eye. (This is the basis for the red eye
>>>>>> effect in
>>>>>> people. We don't have a Tapetum Lucidum.)
>>>>>> Andrew
>>>>>> On 18/11/2013 12:18 PM, Chris Corben wrote:
>>>>>>> Roger
>>>>>>> It's very simple physics. Almost anything looks brightest when
>>>>>>> the light
>>>>>>> source is close to your eyes. But in addition, a bird's eye is
>>>>>>> pretty much
>>>>>>> retro-reflective. That is, the light reflected by it mostly goes
>>>>>>> back along
>>>>>>> the path it came from. If you think about it, you are looking at
>>>>>>> the inside
>>>>>>> of a sphere, so wherever the light comes from, it is reflected
>>>>>>> back in the
>>>>>>> reverse direction. The same principle is used to make road
>>>>>>> markings shine
>>>>>>> brightly at night. The paint on a road is filled with tiny glass
>>>>>>> spheres, so
>>>>>>> that from whatever direction the light arrives, some portion of
>>>>>>> it is
>>>>>>> retro-reflected. Since the headlights of a car are not too far
>>>>>>> off the line
>>>>>>> of your sight, a lot of that light comes back to your eyes, and
>>>>>>> the markings
>>>>>>> look bright. If the paint was just plain gloss paint, it would be
>>>>>>> much more
>>>>>>> reflective, but nearly all the light from the headlights would be
>>>>>>> reflected
>>>>>>> away from the driver, and the paint would look essentially black.
>>>>>>> As does
>>>>>>> smooth ice,
>>>>>   and for the same reason.
>>>>>>> Owlet Nightjars eyes are not nearly so bright as White-throated
>>>>>>> Nightjar's
>>>>>>> eyes. But even a White-throated can be seen at much greater
>>>>>>> distance with a
>>>>>>> light which is close to your eyes. It makes such a difference,
>>>>>>> that you can
>>>>>>> wear a headlamp and see the eyes of things like owls at
>>>>>>> reasonable distance
>>>>>>> even though the headlamp is not very bright. A side benefit of
>>>>>>> this is that
>>>>>>> the lower light levels will scare the bird a lot less, so you can
>>>>>>> actually
>>>>>>> gain by having a lower intensity light if it is close to your
>>>>>>> eyes. A
>>>>>>> headlamp is perfect for that!
>>>>>>> Incidentally, if you know to look for it, you can see eye-shine
>>>>>>> of animals
>>>>>>> in all sorts of unexpected ways. A classic case is to get to a
>>>>>>> place where
>>>>>>> there are frogs on the surface of the water. If you get the sun
>>>>>>> straight
>>>>>>> behind you (eg in early morning or late afternoon), you will be
>>>>>>> able to see
>>>>>>> their eye-shines surprisingly well, especially if you use
>>>>>>> binoculars.
>>>>>>> Using binoculars with a headlamp is a great way to find all sorts of
>>>>>>> creatures at night. Frogs, snakes, geckoes, spiders, small
>>>>>>> mammals and even
>>>>>>> bats in the right situations. Just use your binoculars to look at
>>>>>>> the spot
>>>>>>> of light from the headlamp.
>>>>>>> Cheers, Chris.
>>>>>>> On 11/17/2013 08:39 PM, Roger McNeill wrote:
>>>>>>>> A few weeks ago Gus McNab was over and we were discussing
>>>>>>>> spotlighting and
>>>>>>>> I mentioned how I have a good population of Owlet Nightjars on
>>>>>>>> our block
>>>>>>>> but I never see them at night because their eyes don't eyeshine,
>>>>>>>> despite
>>>>>>>> wandering the woods after hours.
>>>>>>>>   He told me (politely) how wrong I was and the issue was that I
>>>>>>>> was not
>>>>>>>> holding the torch in the right place to see it.  What I needed
>>>>>>>> to do was
>>>>>>>> walk around like a unicorn with the torch beam emenenting from
>>>>>>>> between my
>>>>>>>> eyes.  I (polietly) said that is faseniting, thinking that this
>>>>>>>> was surely
>>>>>>>> some ploy to make me look like an idiot...not that help is
>>>>>>>> required...and
>>>>>>>> thinking how that could possibly be true?
>>>>>>>>   Last night, I had a visiting bird-o who wanted to see
>>>>>>>> Nightjars and other
>>>>>>>> things so we decided to wander the tracks and see what we could
>>>>>>>> find.
>>>>>>>> First try was for White-throated Nightjars...two birds pearched
>>>>>>>> up for us,
>>>>>>>> brilliant eyeshine.  A koala started calling back at the house
>>>>>>>> so we
>>>>>>>> wandered back, yep bright eye shine...we then decided to walk
>>>>>>>> down to
>>>>>>>> "owlet-nightjar grove" and I had three birds respond and two
>>>>>>>> come in, one
>>>>>>>> quite close.  I put the torch on the bird and as expected
>>>>>>>> no-eyeshine...but
>>>>>>>> then I tried Gus' recomendation and move the torch between my
>>>>>>>> eyes and wow,
>>>>>>>> its eyes shown back bright red like a Christmas tree. Amazing!
>>>>>>>> Gus you
>>>>>>>> were right, but I have no idea what the explanitaion was or why
>>>>>>>> this is the
>>>>>>>> case!  Thanks for the tip...wanted to share publically.
>>>>>>>> Cheers,
>>>>>>>> Roger
>>>>>>>>   Roger McNeill
>>>>>>>> Samford Valley, SEQ
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>>>>>> -- 
>>>>>> ***********************************************************
>>>>>> Andrew Hobbs
>>>>>> ***********************************************************
>>>>>> ===============================
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